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Message-ID: <5ef6157c-ed9e-631d-33dc-2380890d12ee@huawei.com> Date: Thu, 17 Aug 2023 21:32:04 +0800 From: Ruan Jinjie <ruanjinjie@...wei.com> To: "Russell King (Oracle)" <linux@...linux.org.uk> CC: <rafal@...ecki.pl>, <bcm-kernel-feedback-list@...adcom.com>, <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>, <opendmb@...il.com>, <florian.fainelli@...adcom.com>, <bryan.whitehead@...rochip.com>, <andrew@...n.ch>, <hkallweit1@...il.com>, <mdf@...nel.org>, <pgynther@...gle.com>, <Pavithra.Sathyanarayanan@...rochip.com>, <netdev@...r.kernel.org> Subject: Re: [PATCH net-next v2 1/4] net: phy: fixed_phy: Fix return value check for fixed_phy_get_gpiod On 2023/8/17 21:10, Russell King (Oracle) wrote: > On Thu, Aug 17, 2023 at 08:16:28PM +0800, Ruan Jinjie wrote: >> Since fixed_phy_get_gpiod() return NULL instead of ERR_PTR(), >> if it fails, the IS_ERR() can never return the error. So check NULL >> and return ERR_PTR(-EINVAL) if fails. > > No, this is totally and utterly wrong, and this patch introduces a new > bug. The original code is _correct_. > >> Fixes: 71bd106d2567 ("net: fixed-phy: Add fixed_phy_register_with_gpiod() API") >> Signed-off-by: Ruan Jinjie <ruanjinjie@...wei.com> >> --- >> drivers/net/phy/fixed_phy.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/net/phy/fixed_phy.c b/drivers/net/phy/fixed_phy.c >> index aef739c20ac4..4e7406455b6e 100644 >> --- a/drivers/net/phy/fixed_phy.c >> +++ b/drivers/net/phy/fixed_phy.c >> @@ -239,8 +239,8 @@ static struct phy_device *__fixed_phy_register(unsigned int irq, >> /* Check if we have a GPIO associated with this fixed phy */ >> if (!gpiod) { >> gpiod = fixed_phy_get_gpiod(np); >> - if (IS_ERR(gpiod)) >> - return ERR_CAST(gpiod); >> + if (!gpiod) >> + return ERR_PTR(-EINVAL); > > Let's look at fixed_phy_get_gpiod(): > > gpiod = fwnode_gpiod_get_index(of_fwnode_handle(fixed_link_node), > "link", 0, GPIOD_IN, "mdio"); > if (IS_ERR(gpiod) && PTR_ERR(gpiod) != -EPROBE_DEFER) { > ... > gpiod = NULL; > } > ... > return gpiod; > > If fwnode_gpiod_get_index() returns -EPROBE_DEFER, _then_ we return an > error pointer. So it _does_ return an error pointer. > > It also returns NULL when there is no device node passed to it, or > if there is no fixed-link specifier, or there is some other error > from fwnode_gpiod_get_index(). > > Otherwise, it returns a valid pointer to a gpio descriptor. > > The gpio is optional. The device node is optional. When > fixed_phy_get_gpiod() returns NULL, it is _not_ an error, it means > that we don't have a GPIO. Just because something returns NULL does > _not_ mean it's an error - please get out of that thinking, because > if you don't your patches will introduce lots of new bugs. Thank you, I understand what you mean, NULL is not an error here, so it is not handled. > > Only when fwnode_gpiod_get_index() wants to defer probe do we return > an error. > > So, sorry but NAK to this patch, it is incorrect. >
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